Open AccessSpectral ageing analysis of the double–double radio galaxy J1453+3308
Author(s) -
Konar C.,
Saikia D. J.,
Jamrozy M.,
Machalski J.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10874.x
Subject(s) - giant metrewave radio telescope , physics , astrophysics , galaxy , spectral line , synchrotron , telescope , radio telescope , radio galaxy , astronomy , optics
We present new radio observations at frequencies ranging from 240 to 4860 MHz of the well‐known, double–double radio galaxy (DDRG), J1453+3308, using both the Giant Metrewave Radio Telescope (GMRT) and the Very Large Array (VLA). These observations enable us to determine the spectra of the inner and outer lobes over a large frequency range and demonstrate that while the spectrum of the outer lobes exhibits significant curvature, that of the inner lobes appears practically straight. The break frequency, and hence the inferred synchrotron age of the outer structure, determined from 16‐arcsec strips transverse to the source axis, increases with distance from the heads of the lobes. The maximum spectral ages for the northern and southern lobes are ∼47 and 58 Myr, respectively. Because of the difference in the lengths of the lobes, these ages imply a mean separation velocity of the heads of the lobes from the emitting plasma of 0.036 c for both the northern and southern lobes. The synchrotron age of the inner double is about 2 Myr which implies an advance velocity of ∼0.1 c , but these values have large uncertainties because the spectrum is practically straight.